The Blessed Virgin Mary, the Mother of God, appeared six times to three shepherd children ("the Three Seers") near the town of Fatima, Portugal between May 13th and October 13th 1917. Appearing to the children, the Blessed Virgin told them that She had been sent by God with a message for every man, woman and child living in our century. Coming at a time when civilization was torn asunder by war and bloody violence, she promised that Heaven would grant peace to the entire world if Her requests for prayer, reparation and consecration were heard and obeyed.
The Catholic Church has officially endorsed the Fatima Message "as worthy of belief" since 1930. Five successive popes have publicly indicated their approval and belief in the validity and critical importance of the Fatima apparitions. Several popes have visited Fatima on solemn pilgrimage and Pope John Paul II has gone at least once in every decade of his pontificate. His Holiness has publicly credited Our Lady of Fatima for saving his life during an assassination attempt in 1981 (which, parenthetically, took place on the 64th anniversary of the first Fatima apparition).
The following year, while in Fatima to give thanks for Her intervention, the Pope stated that "the message of Fatima is more relevant and more urgent" today than even when Our Lady first appeared. The heart of Our Lady's Message to the world is contained in what has come to be called the "Secret" which She confided to the three child seers in July 1917. The Secret actually consists of three parts, the first two of which have been publicly revealed. The first part of the Secret was a horrifying vision of hell "where the souls of poor sinners go" and contained an urgent plea from Our Lady for acts of prayer and sacrifice to save souls. The second part of the Secret specifically prophesized the outbreak of World War II and contained the Mother of God's solemn request for the Consecration of Russia as a condition of world peace. It also predicted the inevitable triumph of Her Immaculate Heart following Russia's consecration and the conversion "of that poor nation" to the Catholic Faith.
The last part of the Secret (often called the "Third Secret") has not yet been made public, but was written down by Lucy Dos Santos, the last living Fatima seer, in 1944 and has been in the possession of the Holy See since 1957. Most informed sources speculate that this portion of the Secret concerns chaos in the Catholic Church, predicting widespread apostasy and a loss of faith beginning in the sixth decade of the 20th century.
In the years since the Queen of Heaven's appearances at Fatima, innumerable books, pamphlets, recordings, films and video programs have been produced as part of a growing worldwide movement of faith and devotion. Many theologians believe that Our Lady's Message is uniquely designed for the difficult and trying times in which we live today and suggest that it is Heaven's intervention to save the world from war, hunger and need, the Catholic Church from apostasy and chaos and the souls of countless millions from eternal damnation. While stern in its warning of the terrible punishments for sin and disobedience, Fatima remains fundamentally a life-affirming and faith-building message of hope and peace for all Catholics and others of good will everywhere.
This information was taken from http://www.fatima.org